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SubjectRe: [PATCH v3 net-next 2/3] net: ipv6: new accept_untracked_na option to accept na only if in-network
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Le 14/07/2022 à 01:40, Jaehee Park a écrit :
> This patch adds a third knob, '2', which extends the
> accept_untracked_na option to learn a neighbor only if the src ip is
> in the same subnet as an address configured on the interface that
> received the neighbor advertisement. This is similar to the arp_accept
> configuration for ipv4.
>
> Signed-off-by: Jaehee Park <jhpark1013@gmail.com>
> Suggested-by: Roopa Prabhu <roopa@nvidia.com>
> ---
> Documentation/networking/ip-sysctl.rst | 51 +++++++++++++++-----------
> net/ipv6/addrconf.c | 2 +-
> net/ipv6/ndisc.c | 29 ++++++++++++---
> 3 files changed, 55 insertions(+), 27 deletions(-)
>
> diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
> index 5c017fc1e24d..722ec4f491db 100644
> --- a/Documentation/networking/ip-sysctl.rst
> +++ b/Documentation/networking/ip-sysctl.rst
> @@ -2483,27 +2483,36 @@ drop_unsolicited_na - BOOLEAN
>
> By default this is turned off.
>
> -accept_untracked_na - BOOLEAN
> - Add a new neighbour cache entry in STALE state for routers on receiving a
> - neighbour advertisement (either solicited or unsolicited) with target
> - link-layer address option specified if no neighbour entry is already
> - present for the advertised IPv6 address. Without this knob, NAs received
> - for untracked addresses (absent in neighbour cache) are silently ignored.
> -
> - This is as per router-side behaviour documented in RFC9131.
> -
> - This has lower precedence than drop_unsolicited_na.
> -
> - This will optimize the return path for the initial off-link communication
> - that is initiated by a directly connected host, by ensuring that
> - the first-hop router which turns on this setting doesn't have to
> - buffer the initial return packets to do neighbour-solicitation.
> - The prerequisite is that the host is configured to send
> - unsolicited neighbour advertisements on interface bringup.
> - This setting should be used in conjunction with the ndisc_notify setting
> - on the host to satisfy this prerequisite.
> -
> - By default this is turned off.
> +accept_untracked_na - INTEGER
> + Define behavior for accepting neighbor advertisements from devices that
> + are absent in the neighbor cache:
> +
> + - 0 - (default) Do not accept unsolicited and untracked neighbor
> + advertisements.
> +
> + - 1 - Add a new neighbor cache entry in STALE state for routers on
> + receiving a neighbor advertisement (either solicited or unsolicited)
> + with target link-layer address option specified if no neighbor entry
> + is already present for the advertised IPv6 address. Without this knob,
> + NAs received for untracked addresses (absent in neighbor cache) are
> + silently ignored.
> +
> + This is as per router-side behavior documented in RFC9131.
> +
> + This has lower precedence than drop_unsolicited_na.
> +
> + This will optimize the return path for the initial off-link
> + communication that is initiated by a directly connected host, by
> + ensuring that the first-hop router which turns on this setting doesn't
> + have to buffer the initial return packets to do neighbor-solicitation.
> + The prerequisite is that the host is configured to send unsolicited
> + neighbor advertisements on interface bringup. This setting should be
> + used in conjunction with the ndisc_notify setting on the host to
> + satisfy this prerequisite.
> +
> + - 2 - Extend option (1) to add a new neighbor cache entry only if the
> + source IP address is in the same subnet as an address configured on
> + the interface that received the neighbor advertisement.
>
> enhanced_dad - BOOLEAN
> Include a nonce option in the IPv6 neighbor solicitation messages used for
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index 88becb037eb6..6ed807b6c647 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -7042,7 +7042,7 @@ static const struct ctl_table addrconf_sysctl[] = {
> .data = &ipv6_devconf.accept_untracked_na,
> .maxlen = sizeof(int),
> .mode = 0644,
> - .proc_handler = proc_dointvec_minmax,
> + .proc_handler = proc_dointvec,
> .extra1 = (void *)SYSCTL_ZERO,
> .extra2 = (void *)SYSCTL_ONE,
Maybe keeping proc_dointvec_minmax with SYSCTL_TWO for extra2 is better to avoid
accepting all values. It enables to add another value later.


Regards,
Nicolas

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